1. Field of the Invention
The present invention relates to a vapor-phase epitaxial growth process for producing a Si single crystal substrate having a Si single crystal film thereon, which is useful for making semiconductor integrated circuits, by epitaxially growing the Si single crystal film on the Si single crystal substrate.
2. Description of Related Art
In the production of semiconductor integrated circuits, the process for producing a Si single crystal substrate having a Si single crystal film by epitaxially growing the Si single crystal film on the Si single crystal substrate is one of some important processes.
This process has such a problem that since it is usually carried out at so high a temperature as 1,000.degree. C. or higher, the autodoping and solid phase diffusion cause dopants in the Si single crystal substrate to penerate into the epitaxially grown Si single crystal film, and defects like slips are formed.
Various processes in which the crystal growth is carried out at a lower temperature to solve the problem above have been proposed.
In one of these processes, an easily decomposable gas is used as a raw material, and as such easily decomposable gas has been proposed, for example, disilane (Si.sub.2 H.sub.6).
It is known that when disilane is used in the vapor-phase epitaxial growth, a crystal can be grown even at 700.degree. C. under atmospheric pressure.
However, the Si single crystal film obtained by the vapor-phase epitaxial growth using disilane at 700.degree. C. under atmospheric pressure still has more than 10.sup.4 /cm.sup.2 of faults and hence is industrially unsatisfactory and further the deposition rate or growing rate of the film is as low as 0.01 .mu.m/min.
Furthermore, when the crystal growth is carried out at a lower temperature for the purpose of reducing the faults, the single crystal is hardly produced, and rather a polycrystal is produced. In order to avoid the production of such a polycrystal, a way such as growth with irradiation of an ultraviolet ray or growth under reduced pressure has been proposed, which way, however, requires complicated apparatuses. Thus, the way is unacceptable from an economical and technological point of view.
The inventors have conducted intensive researches for solving the problems as mentioned above, that is, inhibiting the generation of the stacking faults in the Si single crystal film, decrease of the film deposition rate and production of the polycrystal during the vapor-phase epitaxial growth of the Si single crystal film from disilane on the Si single crystal substrate at a low temperature.